Is Alcohol Helping You Sleep? Not According to Research

It is not uncommon for adults all over the world to enjoy a few glasses of wine or other libation at the end of the day, but if you’re drinking at night to help you sleep, you may be surprised to learn that alcohol actually interferes with restorative sleep, according to research conducted at the Akita University in Japan.

The study was conducted by Yohei Sagawa, a medical doctor in the department of neuropsychiatry at the Akita University School of Medicine, and his colleagues. The researchers were interested in how alcohol affects the parasympathetic nervous system, which controls the body at rest, and the sympathetic nervous system which stimulates the body. In other words, they wanted to know what effect, if any, does alcohol consumption have on sleep and heart rate variability (HRV) — a measure of the time intervals between individual heartbeats — during sleep.

The researchers studied 10 male university students, all healthy and around age 21. The students were divided into three groups, and given three different beverages with different alcoholic contents. One group had a high alcohol content based on their body weight; the second group had a low dose based on body weight; and the third group’s drinks had no alcohol.

On the day of the testing, an electrocardiogram was attached to each student for 24 hours. The students were then asked to consume their drinks 100 minutes before bedtime. While they were sleeping, the researchers measured the student’s heart rates and heart rate variability, and monitored their sleep for eight hours using a polysomnogram.

Results of the Alcohol on Sleep

The results of the study were published last November in the journal, Alcoholism: Clinical & Experimental Research. The researchers found that the students who consumed alcohol fell asleep faster than those who did not consume alcohol, but as the night progressed, their sleep became shallow and disrupted, compared to the students who did not drink alcohol before they went to sleep. Also, the heart rate and heart rate variability testing found that the consumption of alcohol resulted in an increased heart rate and a range of heart rate variability — the greater the amount of alcohol consumed, the more a student’s heart rate increased.

While it is generally believed that having a drink or two before bed may aid sleep, it may only be fact in some people who consume a small amount. The researchers determined that the presence of alcohol in the students acted as a stimulant, increased their heart rates and prevented them from transitioning into a truly deep, restorative state of sleep. In conclusion, they found that alcohol affects overall sleep architecture, and that consuming a large amount of alcohol before bedtime interferes with sleep quality and the restorative role of sleep.